The present invention relates to systems and methods for providing access to pedicles during spinal procedures, for example spinal fusion.
Spinal fusion is a surgical procedure that fuses two or more vertebrae together using bone graft materials supplemented with devices. Spinal fusion may be performed for the treatment of chronic neck and/or back pain, trauma, and neoplasms. Spinal fusion can be used to stabilize and eliminate motion of vertebrae segments that may be unstable, or move in an abnormal way, that can lead to discomfort and pain. Spinal fusion may be performed to treat injuries to the vertebrae, degeneration of spinal discs, abnormal spinal curvature, and/or a weak or unstable spine.
Spinal fusion generally requires a graft material, usually bone material, to fuse the vertebrae together. The bone graft material can be placed over the spine to fuse adjacent vertebrae together. Alternatively, a device may be positioned between the vertebrae being fused and filled with the bone graft material. Such a device can include holes that allow the vertebrae and the graft material to grow together to provide fusion, with the cage supporting the weight of the vertebrae while the fusion is occurring. Because the fusion mass is under pressure, fusion can be promoted. The disc space height can be restored, taking pressure off of the nerves. The spine alignment, for aminal height, and canal diameter can be restored. In some cases the graft can be placed with minimal disruption of muscles and ligaments using minimally invasive approaches to the spine, thus preserving the natural anatomical integrity of the spine. Other interbody device assemblies are also presently known.
Rods may be used to immobilize the vertebrae being fused to allow for improved fusion. Such rods may be mounted to the vertebrae using pedicle screws. The pedicle screws are threaded through the pedicles and into the vertebral bodies. Because of the proximity of the spinal cord as well as additional nerve bodies, such screws must be placed accurately to avoid injury to the nervous system.
To help position devices, such as K-wires, that can be used to orient dilators and pedicle screws being inserted into and/or toward the vertebrae, a hollow needle may be used. For example, with a hollow needle positioned with its distal end abutting or penetrating a pedicle, a K-wire may be inserted into the pedicle, and the needle removed. Dilators may then be used to increase the area of access. The K-wire may then be removed and the pedicle screw installed.
However, the trajectory of the needle must be properly aligned to avoid driving the K-wire, dilators, or pedicle screw into the spinal column or other nerve bodies. X-rays may be used to check the trajectory of the needle. If the trajectory is not acceptable, the needle may be re-oriented and another x-ray taken. Because the trajectory may be difficult to correctly align, a large number of re-orientations and x-rays may be required, such as, for example, 20 x-rays. Holding the needle in place manually exposes the practitioner to repeated radiation. The needle may be provided with a handle, for example, to attempt to help keep the practitioner's hand out of a radiation field. However, due to the distance of the handle from the edge of the needle as well as the inherent instability of manually holding the handle and needle, the trajectory may not remain constant, resulting in the ending trajectory differing from the trajectory at the time of the x-ray.
Various frames, arms, and clamps are known for use with, for example, positioning endoscopes. These devices, however, are not well suited for manipulating the above described devices due, for example, to their size, bulkiness, and interference with an x-ray field.
It is therefore one object of the present invention to provide systems and methods that provide for improved manipulation and positioning of needles or other devices used to access pedicles during spinal procedures.